Automobiles utilize safety restraint systems to protect vehicle occupants. Most vehicle safety systems are designed to mitigate potential injuries to occupants during vehicle crashes. For example, vehicles commonly employ restraint systems which may include safety devices such as front airbags, side airbags, and seatbelt pretensioners. Many of these restraint systems are activated in response to passive accelerometer-based collision detection sensors. Besides the safety systems, which directly act upon vehicle occupants to mitigate potential injuries in the event of a collision, other safety systems are known which are designed to improve the vehicle's ability to dissipate the impact event energy to portions of the vehicle other than the passenger compartment. For example, such safety systems could include bumper airbags or other external airbags, active chassis or front-end stiffening systems, or bumper height adjustment such that the vehicle body structure can bear, to the maximum extent, the impact energy.
Automobile manufacturers are also investigating radar, lidar and vision-based pre-crash sensing systems to improve occupant safety. Such pre-crash sensing systems can be used to deploy active or passive countermeasures to enhance injury mitigation. Such pre-crash sensing systems provide advance warning of imminent collision events such that safety systems can be pre-armed or deployed just prior to impact so that their effectiveness can be maximized. For example, pre-crash sensing systems are highly desirable for effective implementation of external airbag applications.
Most vehicle safety systems, however, typically react or are activated without regard to the target vehicle or detected object dynamics. For instance, vehicle-to-vehicle collision compatibility is an increasingly important safety issue for the automotive industry. That is, the crash compatibility of passenger cars, light trucks and vans in vehicle-to-vehicle collisions could provide potential improvements for passenger safety. An important element in the incompatibility of, for example, passenger cars and light trucks during a collision event, is due to the geometric mismatch in front-to-front and front-to-side collisions. Thus, in cases when a light truck or sport utility vehicle collides with a passenger car, the longitudinal rails of both vehicles are not always directly involved in absorbing the crash energy. Misalignment of these stiff longitudinal rails can result in higher passenger compartment intrusion levels due to less than desirable energy absorption by the stiff elements in mismatched front-to-front and front-to-side collisions.
Accordingly, to reduce the likelihood of occupant injury, there exists a need for safety systems which can avoid geometrical mismatches between vehicles, particularly in front-to-side impact scenarios. Lowering the ride-height of a sport utility vehicle, or increasing the ride-height of a passenger car by a fixed amount before a crash event is one solution being considered within the automotive industry. However, design considerations have resulted in a range of bumper heights, front longitudinal member heights, and side sill heights for various vehicles. In addition, because present safety systems do not account for the dynamic reaction of the target vehicle, the host vehicle may adjust suspension heights based upon driving conditions and the target vehicle may be in the process of correspondingly doing the same. Thus, the possibility of one vehicle increasing its bumper height while the other vehicle is in the process of lowering its bumper height, thereby maintaining or worsening the originally detected geometric mismatch could occur. Further, due to variation in vehicle loads, the vehicle ride-heights before a collision event could also vary. Consequently, there exists a need for new methods and systems to provide improved vehicle-to-vehicle collision compatibility.